Crowley eyed the smooth-talking, higher-ranked demon who was, yes, very practiced and at ease. The Serpent wasn't surprised to discover it was Belial, Prince of Smooth. (Crowley himself was Prince of Flash, though, so he wasn't TOO impressed.)

Giving Belial a nod of respect, Crowley found himself also radiating cool, calm, and collected as he said, "Thank you, Lord Belial, but that won't be necessary. We were just leaving."

In fact, in Crowley's opinion the quicker they were out of there and away from two of his superiors--one of whom wanted to terminate Aziraphale and grind him into a pulp--the better.